The aim of this research is to delineate the role of nerve pathways involving the abdominal prevertebral ganglia in controlling mesenteric blood vessels and to determine the organization of the abdominal nerve-vessel system. Experiments have been designed to determine: (1) characteristics of vascular afferent pathways from mesenteric arteries veins to the sympathetic ganglia; (2) the characteristics of neuromuscular transmissions from sympathetics nerves to mesenteric arteries and veins; (3) the characteristics of intestinal noncholinergic sensory pathways to the prevertebral ganglia: 4) whether there are reflexes between different vascular regions in the mesentery and/or between the mesenteric vasculature and the musculature of the gastrointestinal tract (5) the pharmacologic properties of the reflex pathways within the ganglia and at the nerve-blot vessel junction. These studies will involve anatomical physiological and pharmacologic approaches to these questions. In vitro preparations from guinea pigs, rabbits, rats and cats that consist of the celiac plexus and inferior mesenteric ganglion attached to selected abdominal organs will be used. Preganglionic, postganglionic and afferent nerve fibers will be electrically stimulated. Electrophysiological techniques will be used to determine intracellular responses of neurons in the prevertebral ganglia and vascular smooth muscle cells. Pressure recording techniques will be used to distend and record the contractile responses of mesenteric vascular and gastrointestinal segment. Pharmacologic techniques will be used to determine the mechanisms which modulate neurotransmission in the ganglia and to the blood vessels to determine how these mechanism can be altered with drug therapy. The goal of these studies will be to understand how to autonomic nervous system controls blood vessels and what role reflexes between the viscera plays in this control. This knowledge will help us to understand and design better treatment for diseases which involve the autonomic nervous system; the nerves the selves well as the organs they innervate.